Tire-use rubber-covered fabric, production method therefor, production method for pneumatic tire using rubber-covered fabric, and pneumatic tire

ABSTRACT

A rubber-coated fabric  10  for a tire, obtained by rubber-coating a rattan blind woven stuff  14  in which wefts  11  and warps  12  made of tire cords  13  are woven into a rattan blind form. The wefts  11  have a break elongation of 4 to 30% and a break strength of 3 to 15 N.

TECHNICAL FIELD

[0001] The present invention relates to a rubber-coated fabric for atire which makes it possible to suppress deterioration in the uniformitythereof resulting from joint portions of a carcass ply while keeping thejoint strength at the joint portions, so as to improve the appearancequality and the uniformity of the tire, a process for producing thesame, a process of using a rubber-coated fabric to produce a pneumatictire, and a pneumatic tire.

BACKGROUND ART

[0002] As illustrated in FIG. 9(A), a carcass ply A of a pneumatic tireis formed using, as an original fabric, a long rubber-coated fabric dwherein a rattan blind woven stuff c obtained by weaving warps a andwefts b made of carcass cords into a rattan blind is coated with atopping rubber g.

[0003] Specifically, this rubber-coated fabric d is cut into plural cutpieces d1 at a desired angle θ (about 75 to 90° in a radial tire) to theside-edge of the fabric, and then ends de and de, on the side of theside-edge (on the non-cut side), of the respective cut pieces d1 aresuccessively jointed (primary jointing j1), thereby forming a joint plyf wherein the carcass cords are arranged at the angle θ to the lengthdirection.

[0004] As illustrated in FIG. 9(B), this joint ply f is cut into aconstant length, which corresponds to one circumference, and the cutpiece is wound on a drum along the circumferential direction and thenboth ends fe and fe thereof along the circumferential direction arejointed with each other (secondary jointing j2), thereby forming thecylindrical carcass ply A.

[0005] As illustrated in FIG. 10, in the primary jointing j1 and thesecondary jointing j2, the so-called overlap joint is performed whereinthe ends de and de, as well as the ends fe and fe, are overlapped witheach other and jointed with each other under pressure. At this time, thejoint portions j are formed to have a width jw, wherein four or morecarcass cords overlap with each other in the vertical direction, inorder to keep a necessary joint strength.

[0006] However, such an overlap joint has a problem that because of alarge rigidity difference between the joint portions j and portionsother than them the uniformity is lowered and damaged and further poorappearances called bulges and dents are caused.

[0007] In order to decrease the rigidity difference, it is desired thatthe joint portions j are made to have such a width that the number ofoverlapping carcass cords a is two or less. However, such joints haveinsufficient joint strength. Thus, when the carcass ply A is shaped,there arises a problem that the joint portions j are separated andopened. Thus, the manner has not been carried out.

[0008] In light of such situations, the present inventor made research.As a result, it has been made evident that the separation (opening) ofthe joint portions j is affected by the wefts b. That is, the wefts bare made of thin and weak organic fibers, and at the time of shaping theply, the wefts are stretched in the circumferential direction togenerate power in the direction along which the joint portions j areopened. In particular, the break elongation of conventional wefts is aslarger as 60 to 150%; therefore, the wefts are elongated rather thancut. As a result, the power in the direction along which the jointportions j are opened is made larger.

[0009] The inventor has found out that in the case that the breakelongation of the wefts b are restrained to 30% or less and the breakstrength thereof is restrained into 15 N or less, the wefts b arereadily broken by tensile force at the time of the shaping; therefore,even if the number of the overlapping carcass cords a in the jointportions j is set to 2 or less, the joint portions j can be preventedfrom being separated (opened) . At this time, the wefts b are preferablycut at a given pitch before the shaping. For this purpose, asillustrated in FIG. 11, it is preferred to pass the rubber-coated fabricd before primary jointing through a gap n between a pair of comb-teethform roller r1 and r2 which engage with each other in a convex andconcave manner, cause tension to act on the wefts b, and cut the weftsb. In the figure, symbol s represents a cut portion.

[0010] From further research by the inventor, it has also made clearthat in order to make a further improvement in the uniformity, the cutpitch of the wefts b in side-edge areas E (shown in FIG. 9(A)) of thefabric d is made smaller than the cut pitch in a central area M betweenthe side-edge areas E and E rather than the cut pitch of the wefts b ismade constant (even) over the entire width of the fabric d. The reasonfor this is as follows. In the central area M, the carcass cords a slipout readily from the cut wefts b so as to be free. However, since thewefts b are folded into a lying U-shape in the side-edges of the fabricd, the carcass cords a get entangled to be restrained. As a result, atthe time of the shaping of the carcass ply, intervals between thecarcass cords are made coarse and minute, thereby producing a bad effecton the uniformity.

[0011] As the rattan blind woven stuff c, the following are well known:a woven stuff of a turn type, wherein a single weft b is madecontinuous; and a woven stuff of a tacking-in type, which is composed ofplural tacking-in thread pieces ba wherein both ends of wefts b areterminated at folded portions b3 having a small length, as illustratedin FIG. 9 (A). However, in this tacking-in type woven stuff, the basalportion b1 of the tacking-in thread piece ba and the folded portion b3overlap with each other so as to make an overlap portion in theside-edge area E. Therefore, in this manner, the strength against breakis increased. Additionally, the power of restraining the carcass cords ais higher than that of the turn type. Accordingly, the tendency of thefall in the uniformity gets stronger.

DISCLOSURE OF THE INVENTION

[0012] Thus, objects of the present invention are to provide arubber-coated fabric for a tire which makes it possible to decrease ajoint width largely while keeping joint strength in joint portions of acarcass ply, make intervals between carcass cords uniform when thecarcass ply is shaped, reduce poor tire appearances such as bulges anddents, and improve the uniformity thereof; a process for producing thesame; a process for producing a pneumatic tire using a rubber-coatedfabric; and a pneumatic tire.

[0013] The first invention of the present inventions is a rubber-coatedfabric for a tire, obtained by rubber-coating a rattan blind woven stuffin which wefts and warps made of tire cords are woven into a rattanblind form, characterized in that the wefts have a break elongation of 4to 30% and a break strength of 3 to 15 N.

[0014]1n this rubber-coated fabric, the wefts are preferably cut afterthe rubber-coating is performed, and the cut pitch of the wefts inside-edge areas of the rubber-coated fabric is preferably made smallerthan that in the central area thereof. Preferably, the cut pitch of thewefts in the side-edge areas is set to 1 to 4 times the pitch of theembedded tire cords and the cut pitch of the wefts in the central areais set to 3 to 5 times the pitch of the embedded tire cords.

[0015] A second invention of the present inventions is a process forproducing the rubber-coated fabric wherein wefts are cut afterrubber-coating is performed,

[0016] characterized by comprising a rubber-coating step of coating arattan blind woven stuff obtained by weaving wefts and warps made oftire cords into a rattan blind form with a rubber, thereby forming afabric substrate, and a weft-cutting step of cutting the wefts of thisfabric substrate with a pushing cutter,

[0017] wherein in the pushing cutter a pair of comb-teeth form rollersin which rib-form pushing nail portions extending in the circumferencedirection are arranged at intervals in the axial direction are facedwith each other in parallel to each other and in such manner that thepushing nail portions of one of the comb-teeth rollers do not contactthe inside of concave portions between the pushing nail portions of theother comb-teeth form roller, whereby the pushing cutter has a gap whichis continuous in a convex and concave form in the axial directionbetween the comb-teeth form rollers, and the fabric substrate is passed,in a direction along which the wefts are parallel to the axial directionof the comb-teeth form rollers, between this gap.

[0018] In the comb-teeth form rollers, it is preferred that the width αa of the pushing nail portions in the axial direction and the separatedistance β of the pushing nail portions adjacent to each other in theaxial direction in both end portions in the axial direction of therollers are made smaller than the width α and the separate distance β inthe central portion thereof, respectively.

[0019] A third invention of the present inventions is a process forproducing a pneumatic tire wherein the rubber-coated fabric is used as acarcass ply,

[0020] characterized by comprising a joint ply forming step ofprimarily-jointing side-edge side ends of cut pieces obtained by cuttingthe rubber-coated fabric in a direction which crosses the side-edges ofthe fabric, thereby forming a joint ply, and

[0021] a carcass ply forming step of winding the joint ply in thecircumferential direction on a drum and secondarily-jointing both endsin the circumference direction of this joint ply, thereby forming acylindrical carcass ply,

[0022] wherein the wefts are cut before the carcass ply forming step,and

[0023] in each of the joint portions resulting from the primary jointingand the secondary jointing, not less than three carcass cords do notoverlap vertically.

[0024] The wefts are preferably cut at a stage where the wefts are inthe state of the rubber-coated fabric, and the joint portions arepreferably made up to be butt joints obtained by butting and jointingend faces of the respective ends.

[0025] A fourth invention of the present inventions is a pneumatic tirecharacterized by being produced by the production process described asthe third invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a sectional view illustrating a preferred embodiment ofa pneumatic tire according to the present invention,

[0027]FIG. 2 is a diagram for explaining a joint ply forming step in theprocess for producing a tire,

[0028]FIG. 3 is a diagram for explaining a carcass ply forming step inthe process for producing the tire,

[0029]FIG. 4 is a front view of a pushing cutter,

[0030] FIGS. 5(A) and (B) are an enlarged sectional view of the pushingcutter, and a sectional view of a fabric substrate,

[0031] FIGS. 6(A) and (B) are sectional views of a rubber-coated fabricto show a situation that wefts are cut,

[0032]FIG. 7 is a sectional view of a case in which joint portions areoverlap joints,

[0033] FIGS. 8(A) and (B) are a sectional view of a case in which jointportions are butt joints, and a diagram illustrating a joint methodthereof,

[0034] FIGS. 9(A) and (B) are diagrams for explaining the formation of aconventional carcass ply,

[0035]FIG. 10 is a sectional view for explaining joint portions at thistime, and

[0036]FIG. 11 is an enlarged sectional view illustrating a pushing andcutting step.

BEST MODES FOR CARRYING OUT THE INVENTION

[0037] An embodiment of the present invention will be described on thebasis of the drawings hereinafter. FIG. 1 is a sectional view of apneumatic tire 1 of the present embodiment, wherein a rubber-coatedfabric is used as a carcass ply.

[0038] In FIG. 1, the pneumatic tire 1, which is a radial tire forpassenger tires in the present example, has a tread portion 2, a pair ofside wall portions 3 extending from the both side of the tread portioninwards in the tire radius direction, and a bead portion 4 positioned atthe inner end of each of the side wall portions 3. This pneumatic tire 1is provided with a carcass 6, in a toroid form, striding over the beadportions 4 and 4, and a belt layer 7 arranged inside the tread portion 2and outside the carcass 6 in the tire radius direction.

[0039] The carcass 6 is made of one or more (one in the present example)carcass plies 6A wherein carcass cords are arranged at an angle of 75°to 90° to the tire circumferential direction. As the carcass cords,organic fiber cords made of nylon, polyester, rayon, aromatic polyamideor the like are adopted.

[0040] The carcass ply 6A has a body portion 6 a extending from thetread portion 2 through the side wall portions 3 to bead cores 5 of thebead portions 4, and folded portions 6 b which are continuous to bothsides of the body portion and are folded outwards from the inside of thetire in the axial direction thereof around the bead cores 5, so as to beengaged. Between this body portion 6 a and the folded portion 6 b isarranged a bead apex rubber 8 extending in a tapered form outwards inthe tire radius direction from the bead core. Thus, the bending rigidityof the bead portion 4 is made high.

[0041] The belt layer 7 is made of two or more (two in the presentexample) belt plies 7A and 7B wherein belt cords are inclined andarranged at an angle of 10° to 35° to the tire circumferentialdirection. The respective belt plies 7A and 7B are arranged in such amanner that the belt cords are arranged in different directions so as tocross each other in the different plies. As a result, the belt pliesexhibit hoop effect. As the belt cords, steel cords are preferred. Forexample, however, highly-elastic organic fiber cords made of aromaticpolyamide fibers, aromatic polyester fibers or the like may be used.

[0042] Next, the pneumatic tire 1 is formed by a tire-producing processdescribed hereinafter. This tire-producing process comprises a joint plyforming step S1 (shown in FIG. 2) and a carcass ply forming step S2(shown in FIG. 3). A raw tire formed by this is vulcanized and shaped inthe same way as in the prior art, thereby forming the tire 1.

[0043] As illustrated in FIG. 2, in the joint ply forming step S1, ajoint ply 18 is formed using, as an original fabric, a longrubber-coated fabric 10, two side-edges of which are parallel to eachother. The rubber-coated fabric 10 is formed by subjecting a rattanblind woven stuff 14 obtained by weaving fine wefts 11 and warps 12 madeof organic fiber carcass cords 13 into a rattan blind form to dippingtreatment (adhesive-applying treatment) and then coating both surfacesthereof with a topping rubber 15.

[0044] The rubber-coated fabric 10 is cut, at a desired angle θ (about75 to 90° in any radial tire) to side-edges thereof, into plural cutpieces 10A having a length corresponding to the width of the carcassply. Thereafter, side-edge side (non-cut side) ends 10 of the respectivecut pieces 10A are successively jointed (primary jointing J1), therebyforming the joint ply 18 wherein the carcass cords 13 are arranged atthe angle θ to the long direction thereof.

[0045] Next, in the carcass ply forming step S2, the joint ply 18 is cutinto constant sizes. The resultant cut piece is wound on a drum in thecircumferential direction thereof, and further two ends 18 e in thecircumferential direction of the cut piece are jointed (secondaryjointing J2), thereby forming the cylindrical carcass ply 6A.

[0046] The matter which is largely different from the prior art is that,as the wefts 11, threads that are far more readily broken as comparedwith conventional threads, wherein the break elongation thereof is setwithin the range of 4 to 30% and the break strength thereof is setwithin the range of 3 to 15 N, are used. The “break elongation” is amaximum elongation (%) when tensile load is gradually applied to thewefts so that the wefts are broken. The measurement thereof is performedunder the following conditions: distance between check points: 250 mm,initial load: 0.1 N, and test speed: 300 mm/minute. The strength whenthe wefts are broken is used as the “break strength”.

[0047] The break elongation and the break strength can be set within theabove-mentioned ranges by adjusting the material, the thickness, thetwisted structure etc. of the used organic fibers (examples of whichinclude synthetic fibers, and natural fibers). For example, by usingcotton yarn (thickness: No. 20), the break elongation can be set to therange of 5 to 8%, and the break strength can be set to the range of 4 to5 N.

[0048] Another matter different from the prior art is that the wefts 11are beforehand cut before the carcass ply forming step particularlylimited if the timing is before the carcass ply forming step S2 andafter the dipping treatment of the rattan blind woven stuff 14.Preferably, the wefts 11 are already cut before the time when therubber-coated fabric 10 is formed, in order to keep operation efficiencyand the quality of the ply, or to make the uniformity and so on better.

[0049] The rubber-coated fabric 10 wherein the wefts 11 are beforehandcut can be formed by a production process including a rubber coatingstep of coating the rattan blind woven stuff 14 with the topping rubber15 to form a fabric substrate 16, and a weft cutting step of cutting thewefts 11 of this fabric substrate 16 with a pushing cutter 20.

[0050]FIG. 2 illustrates, as an example, a case in which the rattanblind woven stuff 14 is obtained by tacking-in type weaving into arattan blind form. That is, the wefts 11 is made of tacking-in threadpieces 17 composed of a basal portion 17 a which goes alternately on andbeneath the carcass cords 13 and extends perpendicularly to the carcasscords 13 over almost all of the width of the rattan blind woven stuff14, and folded portions 17 c which extend through secondary portions 17b extending from both ends of the basal portion in parallel to thecarcass cords 13, so as to be folded inwards, extended by a small lengthand terminated. The tacking-in thread pieces 17 are arranged in thelongitudinal direction of the carcass cords 13 at a pitch Lsubstantially equal to the length of the secondary portions 17 b,thereby forming the wefts.

[0051] The length W3 of the folded portions 17 c is not particularlylimited. However, if the length W3 is too small, the tacking-in threadpieces 17 readily get loose. If the length W3 is too large, the effectof improving the productivity gets small. Therefore, the length W3 isdesirably set to at least 20 mm, preferably within the range of 20 to300 mm, more preferably 30 to 70 mm. In the fabric substrate 16 usingthis rattan blind woven stuff 14, the basal portion 17 a of the weft 11and the folded portion 17 c thereof, the two, overlap with each other ineach side-edge area E, which constitutes an area having a width W1 of atleast 20 mm from the side-edge of the fabric substrate 16 into the widthdirection. However, in other portions than the areas E, that is, in acentral area M, which is between the side-edge areas E and E, the weft11 is made of only one of the basal portion 17 a.

[0052] In the weft cutting step, the wefts 11 of the fabric substrate 16are cut with the pushing cutter 20. The fabric substrate 16 is alreadycoated with the topping rubber 15; therefore, even if the wefts 11 arecut at this stage, inconveniences such that the arrangement of thecarcass cords 13 are disturbed do not arise.

[0053] For example, as illustrated in FIG. 4, the pushing cutter 20comprises a pair of comb-teeth form rollers 21 and 21 arranged inparallel to each other. In each of the comb-teeth form rollers 21, acylindrical basal axial portion 22 thereof extending in the axialdirection has rib-form pushing nail portions 23 projecting from thecircumferential surface thereof and extending in the circumferentialdirection, the pushing nail portions 23 being arranged at intervals inthe axial direction. In each of the comb-teeth form rollers 21, bothends thereof are rotatably supported by non-illustrated bearings, andfurther the rollers are rotated and driven in directions reverse to eachother by means of a motor or the like.

[0054] In the pushing cutter 20, the outer circumferential face 23 a ofthe pushing nail portions 23 of one 21A of the comb-teeth form rollersis faced with the inside of concave portions between the pushing nailportions 23 and 23 of the other comb-teeth form roller 21B in such amanner that they do not contact each other. In this way, the pushingnail portions 23 facing each other are engaged with each other, and agap 25 which is continuous in a convex and concave form in the axialdirection is formed between the pair of the comb-teeth form rollers 21Aand 21B.

[0055] The fabric substrate 16 is passed through this gap 25. At thistime, the wefts 11 are set in a direction parallel to the axialdirection of the comb-teeth form rollers 21. In this way, the fabricsubstrate 16 is stretched into a wave form and a tension is appliedthereto, as illustrated in FIG. 11. By combination of this operationwith the matter that the break elongation and the break strength of thewefts 11 are small, cut portions 9 of the wefts 11 can be surely cut ata desired fine cut pitch CP corresponding to the formation pitch of thepushing nail portions 23. It is sufficient that the engaged height ybetween the rollers 21 and 21 is small; therefore, the disturbance ofthe cords after being cut and the waving of the fabric substrate 16 canbe suppressed at a low level. In the cut portions 9, for example, atportions where two of the wefts 11 overlap in the side-edge areas E, itis sufficient that at least one thereof is cut.

[0056] Since the wefts 11 are beforehand cut in this way, it is possibleto suppress the matter that the wefts 11 are stretched in thecircumferential direction at the time of shaping the carcass ply so thatpower having a direction along which the joint portions J are openedacts on the portions J. Even if the length of the wefts 11 after beingcut is long to some degree, the break elongation and the break strengthof the wefts 11 are small; therefore, the wefts 11 are automatically cutby tension at the time of the shaping, so that the opening-directionpower which acts on the joint portions J gets small.

[0057] In the case that the break elongation of the wefts 11 is morethan 30% and the break strength is more than 15 N, the wefts 11 are notreadily cut with the pushing cutter 20 so as to bring a risk that thejoint portions J are opened at the time of the shaping. If the breakelongation is less than 4% and the break strength is less than 3N, thewefts are readily broken when the wefts are woven into a rattan blindform or subjected to dipping treatment. As a result, cord-disturbance iscaused. Thus, the wefts do not exhibit their original function. Fromsuch a viewpoint, the break elongation is preferably from 4 to 25%, morepreferably from 4 to 15%, and still more preferably from 4 to 10%. Thebreak strength is preferably from 3 to 13 N, more preferably from 3 to10 N, and still more preferably 3 to 7 N.

[0058] The opening-direction power which acts on the joint portions Jgets small. In the present invention, therefore, even if the primaryjointing J1 and the secondary jointing J2 are made up to be overlapjoints, the jointing can be attained in such a manner that three or morecarcass cords 13 do not overlap vertically, that is, so as to have sucha width JW that the number of the overlapping carcass cords 13 is two orless, as illustrated in FIG. 7. As illustrated in FIG. 8(A), respectiveend faces S of the ends 10 e and 10 e (or respective end faces 18 e and18 e of the ends 18 e) can be butted and jointed, whereby a butt jointin which the number of the overlapping carcass cords 11 is zero can beadopted.

[0059] It is therefore possible to keep joint strength necessary for thejoint portions J and simultaneously decrease the jointing width largely,so as to improve the uniformity while decreasing poor appearances suchas budges and dents.

[0060] In the above-mentioned butt joint, in order to make thepressure-bonding power to the respective end faces S, it is preferred touse a pair of upper conical comas 30U and 30U and a pair of lowerconical comas 30L and 30L, as illustrated in FIG. 8(B), to bond thejoint portions. About the comas, the upper comas 30U are described as arepresentative. The comas are arranged in such a manner that minimumdiameter portions 31A of their conical faces 31 are brought near eachother and further rotary axial cores N are inclined at such an anglethat the lowest generating line 32 of each of the conical faces 31 isparallel to the ply. The comas 30 are controlled to be rotated at thesame speed. In the rotation, the comas 30 are urged in a direction alongwhich the respective end faces S and S are butted against each other. Inthis way, the joint strength can be made high.

[0061] As a result of research by the inventor, the following has beenproved: in order to make the uniformity and so on higher, as illustratedin FIGS. 6(A) and (B), it is preferred that the cut pitch CP2 in theside edge areas E of the fabric 10 is made smaller than the cut pitchCP1 in the central area M rather than the cut pitch CP of the wefts 11is made constant (even) over the entire width of the fabric 10.

[0062] The reason for this is as follows: The power of the cut wefts 11for restraining the carcass cords 13 is higher in the side edge areas Ethan in the central area M, as described above, so that the intervalsbetween the carcass cords become uneven, for example, the intervals inthe side edge areas E become dense and the intervals in the central areaM become thin at the time of the shaping; therefore, a bad effect isproduced on the uniformity. In particular, in the case that the rattanblind woven stuff 14 is of the above-mentioned tacking-in type, two ofthe wefts 11 overlap in the side edge areas E. Thus, the tendency of thedeterioration in the uniformity gets more intense. It is thereforepreferred to set the ratio between the cut pitches, CP1/CP2, to lessthan 1.0.

[0063] For this purpose, as illustrated in FIG. 4, in the comb-teethform roller 21 of the present example, the width α of the pushing nailportions 23 in the axial direction and the separate distance β betweenthe pushing nail portions 23 which engage with each other are smaller intwo end portions 26 for pushing and cutting the side edge areas E of thefabric substrate 16 than in a central portion 27 for pushing and cuttingthe central area M, as illustrated in FIG. 5(A). The width W1 of theside edge area E from the side edge is preferably from 20 to 300 mm,more preferably from 30 to 70 mm.

[0064] In the central portion 27, the width a of the pushing nailportions 23 is desirably set to about 1.4 to 1.6 times the pitch P ofthe embedded carcass cords 13 in the fabric substrate 16, as illustratedin FIG. 6(B). In the central portion 27, the separate distance β isdesirably set to 1.4 to 1.7 times, more preferably 1.45 to 1.60 timesthe thickness t of the fabric substrate 16. In the central portion 27,the engaging height γ, which is an overlapping height in the radiusdirection of the pushing nail portions which engage with each other, isdesirably set to about 1.4 to 2.0 times, more preferably about 1.6 to1.8 times the pitch β of the embedded carcass cords 13. The distance δin the radius direction between the outer circumferential face 23 a ofthe pushing nail portion 23 and the outer circumferential face 22 a ofthe basal axial portion 22 is preferably set to about 1.1 to 5.0 timesthe thickness t of the fabric substrate 16 in order to pass the fabricsubstrate 16 smoothly therebetween.

[0065] According to this central portion 27 of the comb-teeth formroller, the central area M of the fabric substrate 16 is pushed and cut.Thus, as illustrated in FIG. 6(A), the wefts 11 can be cut at a cutpitch CP1 which is about 3 to 5 times the pitch P of the embeddedcarcass cords 13. This cut pitch CP1 may not be constant if the cutpitch is within the above-mentioned range.

[0066] On the other hand, at the two end portions 26 and 26 of thecomb-teeth form roller 21, it is desired that the width α of the pushingnail portion 23 is set to about 0.8 to 1.2 times the pitch P and theseparate distance β is set to about 1.2 to 1.3 times the thickness t. Asa result, in the two end portions 26 and 26, the wefts 11 can be cut ata cut pitch CP2 which is within the range of 1 to 5 times, morepreferably 2.5 to 3.5 times the pitch β and is smaller than the cutpitch CP1, as illustrated in FIG. 6(B).

[0067] The engaging height γ in the two end portions 26 is notparticularly limited. However, if the height is too large, the carcasscords 13 are readily loosened. If the height is too small, the effect ofpushing and cutting the wefts 11 is apt to be lowered. Thus, theengaging height γ is desirably set to about 0.8 to 1.5 times, morepreferably 1.0 to 1.2 times the pitch P of the embedded carcass cords13. The distance δ is set to a distance substantially equal to that inthe central portion 27.

[0068] As described above, in the present example, the cut pitch CP2 ofthe wefts 11 in the side edge areas E is made smaller than the cut pitchCP1 in the central area M; therefore, the power of the cut wefts forrestraining the carcass cords 13 can be decreased in the side edge areasE. When the carcass ply is shaped, the interval between the carcasscords can be made uniform. As a result, the uniformity can be still moreimproved. For the improvement in the uniformity, the ratio between thecut pitches, CP1/CP2, is preferably set within the range of 1.1 to 2.0,more preferably 1.2 to 1.4.

[0069] The above has described particularly preferred embodiments of thepresent invention. However, the present invention is not limited to theillustrated embodiments, and can be made into various embodiments andcarried out.

Embodiment A

[0070] Radial tires (tire size: 195/65R15) for passenger cars wherein arubber-coated fabric having a basic structure illustrated in FIG. 1 andeach specification shown in Table 1 was used for a carcass ply wereproduced by way trial on the basis of the tire-producing process of thepresent invention, and further the uniformity and the appearance qualityof the respective trial tires were tested. In the embodiment A, thewefts in the side edge areas of the rubber-coated fabric and the weftsin the central area were cut at the same cut pitch CP.

[0071] (1) Uniformity:

[0072] According to JASOC607 (method for testing the uniformity of tiresfor cars), the low-speed RFV, the high-speed RFV and the high-speed TFVof the trial tires (the number of each thereof: 5) were measured underan internal pressure of 200 kPa and a load of 4510 N. They are shown asaverage values. The low-speed value is a value when the circumferentialspeed was 7 km/h, and the high-speed value is a value when thecircumferential speed was 120 km/h.

[0073] (2) Appearance Quality:

[0074] An internal pressure (200 kPa) was applied to each of the trialtires, and the degree that bulges and dents were generated in the sidewall surface thereof was subjected to functional evaluation byinspector's visual observation. The evaluation is shown by five scores.As the value is larger, the appearance is better. TABLE 1 ComparativeExample Example A1 Carcass cords Material Polyester Polyester Thickness1500 dtex/2 1500 dtex/2 Wefts Material Polyester/ Cotton cottonThickness Corresponding No. 20 to 700 dtex Break elongation (%) 100 5Break strength (N) 5 5 Joint type Overlap joint Overlap joint (Thenumber of the 5 1 overlapping cords) Step of cutting the wefts Notcarried out Carried out Separation of the joint Not carried out Notcarried out portion(s) Uniformity Low-speed RFV <N> 60 50 High-speed RFV<N> 120 100 High-speed TFV <N> 80 40 Appearance quality 3 4.5

[0075] As shown in Table 1, in the embodiment A1, the break elongationand the break strength of the wefts were decreased into the given rangeand further the wefts were beforehand cut with comb-teeth form rollers.Therefore, the jointing width thereof was able to be largely decreasedwhile a necessary jointing strength was kept. Thus, it was proved thatthe appearance quality and the uniformity thereof were improved.

Embodiment B

[0076] As described in Table 2, the width α of the pushing nail portionsat two end portions of each comb-teeth form roller and the separatedistance β, and the engaging height γ were varied, and radial tires(tire size: 195/65R15) for passenger cars using, as a carcass ply, arubber-coated fabric wherein the weft cut pitch CP2 in the side edgeareas and the weft cut pitch CP1 in the central area were made differentwere produced by way trial on the basis of the tire-producing process ofthe present invention, and further the uniformity and the appearancequality of the respective trial tires were tested.

[0077] (1) Uniformity:

[0078] According to JASOC607, the high-speed RFV (circumferential speed:140 km/h) of each of the trial tires was measured under an internalpressure of 200 kPa and a load of 4510 N. The results are shown asindexes obtained by regarding the result of Example A2 as 100. As thevalue is larger, the result is better.

[0079] (2) Appearance Quality:

[0080] An internal pressure (300 kPa) was applied to each of the trialtires, and the degree that bulges and dents were generated in the sidewall surface thereof and the waving state (undulation) of the side wallsurface waved were synthetically judged by inspector's visualobservation and by his sense of touch. The results are shown as indexesobtained by regarding the result of Example A2 as 100. As the value islarger, bulges, dents and undulation are more inconspicuous so that theresults are better. TABLE 2 Example A2 Example B1 Example B2 Example B3Example B4 Example B5 Wefts Material Cotton Cotton Cotton Cotton CottonCotton Break elongation (%)  10  10  10  10  10  10 Break strength (N) 10  10  10  10  10  10 Magnitude between cut CP1 ≈ CP1 > CP1 > CP1 >CP1 > CP1 > pitches CP1 and CP2 CP2 CP2 CP2 CP2 CP2 CP2 Side edge areaswidth W1 (mm)  0  20 300  50  50  50 Specification Two end α 1.5 P 1.0 P1.0 P 0.8 P 0.7 P 1.2 P of portions β 1.5 t 1.25 t  1.25 t  1.2 t 1.1 t1.3 t comb-teeth γ 1.6 P 1.2 P 1.2 P 0.8 P 0.7 P 1.5 P rollers Central α1.5 P 1.5 P 1.5 P 1.5 P 1.5 P 1.5 P portion β 1.5 t 1.5 t 1.5 t 1.5 t1.5 t 1.5 t γ 1.6 P 1.6 P 1.6 P 1.6 P 1.6 P 1.6 P Test results Bulgesand dents (index) 100 120 120 120 110 105 Undulation (index) 100 120 110100  95 110 Uniformity (index) 100 120 120 120 110 110

[0081] As shown in Table 2, in embodiments B1 to B5, the weft cut pitchCP2 in the side edge areas was made smaller than the weft cut pitch CP1in the central area; therefore, it was proved that the distance betweenthe carcass cords was made more uniform when the tire was inflated andbulges, dents and the uniformity were more improved as compared withembodiment A2, wherein the pitch was constant (CP1˜CP2). In embodimentB4, the width α of the pushing nail portions and the separate distance βin the comb-teeth form rollers were too small. Thus, the wavedeformation of the fabric substrate was intense so that the undulationwas lowered.

Industrial Applicability

[0082] As described above, the rubber-coated fabric according to thepresent invention is useful for forming a carcass ply of a pneumatictire, and is helpful in decreasing poor appearances of the tire, such asbulges and dents, and improving the uniformity.

1. A rubber-coated fabric for a tire, obtained by rubber-coating arattan blind woven stuff in which wefts and warps made of tire cords arewoven into a rattan blind form, characterized in that the wefts have abreak elongation of 4 to 30% and a break strength of 3 to 15 N.
 2. Therubber-coated fabric for a tire according to claim 2, characterized inthat the wefts have cut portions obtained by being cut after therubber-coating.
 3. The rubber-coated fabric for a tire according toclaim 2, characterized in that the cut pitch between the cut portions inside edge areas, which are areas having a width of at least 20 mm fromeach side edge of the rubber-coated fabric, is smaller than the cutpitch between the cut portions in a central area between the side edgeareas.
 4. The rubber-coated fabric for a tire according to claim 3,characterized in that the cut pitch in the side edge areas is from 1 to4 times the embedding pitch of the tire cords, and the cut pitch in thecentral area is from 3 to 5 times the embedding pitch of the tire cords.5. The rubber-coated fabric for a tire according to any one of claims 1to 4, characterized in that in the wefts, plural tacking-in threadpieces composed of a basal portion which extends over almost all of thewidth of the rattan blind woven stuff, and folded portions which extend, through secondary portions extending from both ends of the basalportion in parallel to the tire cords, so as to be folded inwards andterminated at the side edge areas are arranged at a pitch intervalsubstantially equal to the length of the secondary portions in the warpdirection.
 6. A process for producing the rubber-coated fabric for atire according to claim 2, characterized by comprising a rubber-coatingstep of coating a rattan blind woven stuff obtained by weaving wefts andwarps made of tire cords into a rattan blind form with a rubber, therebyforming a fabric substrate, and a weft-cutting step of cutting the weftsof this fabric substrate with a pushing cutter, wherein in the pushingcutter a pair of comb-teeth form rollers in which rib-form pushing nailportions extending in the circumference direction are arranged atintervals in the axial direction are faced with each other in parallelto each other and in such manner that the pushing nail portions of oneof the comb-teeth rollers do not contact the inside of concave portionsbetween the pushing nail portions of the other comb-teeth form roller,whereby the pushing cutter has a gap which is continuous in a convex andconcave form in the axial direction between the comb-teeth form rollers,and the fabric substrate is passed, in a direction along which the weftsare parallel to the axial direction of the comb-teeth form rollers,between this gap.
 7. The process for producing the rubber-coated fabricfor a tire according to claim 6, characterized in that about the pushingcutter, the width α of the pushing nail portions in the axial directionand the separate distance β of the pushing nail portions adjacent toeach other in the axial direction in both end portions in the axialdirection of the comb-teeth form rollers are made smaller than the widthα and the separate distance β in the central portion thereof,respectively.
 8. A process for producing a pneumatic tire wherein therubber-coated fabric according to claim 1 is used as a carcass ply,characterized by comprising a joint ply forming step ofprimarily-jointing side-edge side ends of cut pieces obtained by cuttingthe rubber-coated fabric in a direction which crosses the side-edges ofthe fabric, thereby forming a joint ply, and a carcass ply forming stepof winding the joint ply in the circumferential direction on a drum andsecondarily-jointing both ends in the circumference direction of thisjoint ply, thereby forming a cylindrical carcass ply, wherein the weftsare cut before the carcass ply forming step, and in each of the jointportions resulting from the primary jointing and the secondary jointing,not less than three carcass cords do not overlap vertically.
 9. Theprocess for producing the pneumatic tire according to claim 8,characterized in that the wefts are cut after the rattan blind wovenstuff is rubber-coated in the rubber-coated fabric for a tire.
 10. Theprocess for producing the pneumatic tire according to claim 8 or 9,characterized in that jointing portions resulting from the primaryjointing and/or the secondary jointing are butt joints wherein the endfaces of the ends are butted and jointed.
 11. A pneumatic tire,characterized by being produced by the production process according toany one of claims 8 to 10.